Protractor



(No Model.)

D. J. KELSEY.

PROTRAGTOR.

Patented July 29, 1890.

INVENTOR UNITED STATES PATENT OFFICE.

DUANE .I. KELSEY, OF NEIV HAVEN, CONNECTICUT.

PROT-RACTO R.

SPECIFICATION forming part of Letters Patent No. 433,084, dated July 29, 1890.

Application filed September 10, 1889. Serial No. 323,567. (No model.)

To all whom it may concern.-

Be it known that I, DUANE J. KELsEY, a citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented a new and useful Protractor, of which the following is a specification.

My invention relates to improvements in protractors, in which a piece bearing rulingedges is pivoted to a frame which is moved along a straight edge to be used in conjunction with it; and the objects of my improvement are, first, to provide an adjustable protractor with ruling-edges at right angles to each other to enable lines and their perpendicular-s to be drawn at any given angle with the straight edge at one setting of the protractor, and, second, to provide a convenient device for setting the instrument at particular angles. I attain these objects by the mechanism illustrated in the accompanying drawings, in which Figure 1 is a top view of the instrument, and Fig. 2 is a vertical section on the line 1 2, Fig. 1.

The piece A constitutes a frame with a straight edge a, which rests against or slides along a straight edge to be used in conjunction with the instrument. At the opposite end of A is a pin C, about which there turns a piece D, having two ruling-edges (Z d at right angles to each other and a graduated are e. The piece D also has notches f ff f f, cut so that the edges (Z d shall lie at particular angles with the straight edge a of the frame when the stopE engages these notches. The stop E is pivoted to A at g, so that by pressing down one end of Eone set of notches fff may be engaged and the other set ff disengaged, or by bringing E to a horizontal position both sets of notches are disengaged and the piece I) is free to turn about A through its entire range. The range of turning of D about A is such that the angles made by the two ruling-edges (Z (Z with the straight-edge a will include all angles from naught to three hundred and sixty degrees. The piece A has a hole through it at h, which shows a portion of the graduated are c, and an index 2', attached to the under side of A,

thus allowing the angle through which D is turned with respect to A to be easily read. A spring F prevents a too-easy turning of D about the pin C, while a set-screw gives additional security when desired.

I am aware that prior to my invention protractors have been made having a piece bearing ruling-edges and a graduated are so arranged as to turn within or upon a frame, which latter is held against a straight edge to be used in conjunction with it. I therefore do not claim such a combination, broadly; but

\Vhat I do claim as my invention, and tie sire to secure by Letters Patent, is

1. The combination, in a protractor, of a graduated arc and two ruling-edges at right angles to each other, all in the same or parallel planes, the whole constituting a'movable piece arranged to turn upon a circular bearing concentric with the graduated are and supported by a frame, said frame eontaining a straight or guiding edge, an opening with an index over the graduated arc, and the aforesaid bearing for the movable piece, also a clip and set-screw for securing said movable piece, the center of said bearing and index being upon a line of symmetry of 'the frame perpendicular to its guidingedge, the whole arranged to lie smoothly upon a plane passing through said rulingedges, all substantially as set forth.

2. The combination,in aprotractor having a movable piece D, with ruling-edges (I d, arranged to turn upon a bearing in a frame A, said frame containing a straight or guiding edge a, of a stop E,pivoted to frame A, so as to rock in a slot in the latter in a plane perpendicular to that of the turning of the movable piece D aboutits bearing in the frame A, and arranged so as to be forced by the operators finger into or out of contact with certain notches in the movable piece D, whereby the latter may be readily set to particular angles with respect to the frame A, substantially as set forth.

DUANE .I. KELSEY. \Vitnesses:

LoUIs D. BEEHER, FRED. A. YEOMANS. 

